The Prediction of Particle Size and Molecular Weight Distributions in Emulsion Polymerization

Control of emulsion polymerization reactors

“…Discussion on population balances can be found in Hulburt and Katz (1964), Randolph (1964), and Ramkrishna (1985). Population balances have been used in modeling the PSD in emulsion polymerization by several investigators (Nomura et al, 1971;Sundberg and Eliassen, 1971;Stevens and Funderburk, 1972;Min and Ray, 1974;Thompson and Stevens, 1977;Kirillov and Ray, 1978;Cauley et al, 1978;Min and Ray, 1978;Min and Gostin, 1979;Sundberg, 1979;Gilbert et al, 1984;Rawlings and Ray, 1988).…”

“…The work of Sundberg and Eliassen (1971) presents an early effort to predict particle size and molecular weight distributions using population balances. The authors treated only micellar nucleation in a batch reactor assuming that radical entry into both the micelles and the particles is proportional to their surface area, that termination occurs either by chain transfer to monomer or by combination with a second radical entering the particle, and that all radicals produced in the aqueous phase are absorbed into the micelles or polymer particles.…”

“…These radicals instead of being terminated are being transferred to other molecules where they will continue growing. The modeling of MWD is much simpler in the case of transfer to monomer or transfer agents, and compartmentalization has no major effect on the breadth of the MWD (Gerrens, 1959;Sundberg and Eliassen, 1971;Napper et al, 1981). Fortunately, for most commercial recipes, chain transfer agents are used extensively for MW control.…”

“…Another case in which particle size does not influence MW is in the polymerization of styrene. Sundberg and Eliassen (1971) predicted a MWD of the Flory type with a polydispersity of 2 for the polymerization of styrene in a well mixed batch reactor. These authors considered that termination takes place by chain transfer to monomer or instantaneous recombination.…”